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How to add another VLAN to a Cisco Router

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Last Modified: 2020-12-21
Hi -

I have three stacked C3750E core L3 switches, that connect to some stacked L2 cisco switches  WS-C2960S-48FPS-L. I am trying to add a new VLAN with the following network subnet/IP- 172.22.23.0/24 - NOW Below are my interface information and I noticed that I have a VLAN120 which is our active wired VLAN. You will see below that this VLAN has 172.22.23.254 which I believe is the default gateway for 172.22.22.0/22? I am confused here, and believe maybe the 172.22.23.0 is already present? I connected my laptop to the interface assigned to VLAN120 on the L2 switch and I received a 172.22.22.0 - Address. I am trying to create a network subnet for another network for 172.22.23.0/24?

On my L2 and L3 switches currently

interface Vlan120
 description Wired Clients
 ip address 172.22.23.254 255.255.252.0
 ip helper-address 172.22.11.10
 no ip proxy-arp

Interface              IP-Address      OK? Method Status                Protocol
Vlan1                  unassigned      YES NVRAM  administratively down down
Vlan101                172.22.1.254    YES NVRAM  up                    up
Vlan107                172.22.7.254    YES NVRAM  up                    up
Vlan108                172.22.8.254    YES NVRAM  up                    up
Vlan109                172.22.9.254    YES NVRAM  up                    up
Vlan110                172.22.10.254   YES NVRAM  up                    up
Vlan111                172.22.11.254   YES NVRAM  up                    up
Vlan113                172.22.13.254   YES NVRAM  up                    up
Vlan114                172.22.14.254   YES NVRAM  up                    up
Vlan120                172.22.23.254   YES manual up                    up
Vlan124                172.22.24.254   YES NVRAM  up                    up
Vlan131                172.22.31.254   YES NVRAM  up                    up
FastEthernet0          unassigned      YES NVRAM  administratively down down
GigabitEthernet1/0/1   unassigned      YES unset  up                    up
GigabitEthernet1/0/2   unassigned      YES unset  down                  down
GigabitEthernet1/0/3   unassigned      YES unset  down                  down
GigabitEthernet1/0/4   unassigned      YES unset  down                  down
GigabitEthernet1/0/5   unassigned      YES unset  down                  down
GigabitEthernet1/0/6   unassigned      YES unset  down                  down
GigabitEthernet1/0/7   unassigned      YES unset  down                  down
GigabitEthernet1/0/8   unassigned      YES unset  down                  down
GigabitEthernet1/0/9   unassigned      YES unset  down                  down
GigabitEthernet1/0/10  unassigned      YES unset  down                  down
GigabitEthernet1/0/11  unassigned      YES unset  down                  down
GigabitEthernet1/0/12  unassigned      YES unset  down                  down
GigabitEthernet1/0/13  unassigned      YES unset  down                  down
GigabitEthernet1/0/14  unassigned      YES unset  down                  down
GigabitEthernet1/0/15  unassigned      YES unset  down                  down
GigabitEthernet1/0/16  unassigned      YES unset  down                  down
GigabitEthernet1/0/17  unassigned      YES unset  up                    up
GigabitEthernet1/0/18  unassigned      YES unset  up                    up
GigabitEthernet1/0/19  unassigned      YES unset  up                    up
GigabitEthernet1/0/20  unassigned      YES unset  up                    up
GigabitEthernet1/0/21  unassigned      YES unset  up                    up
GigabitEthernet1/0/22  unassigned      YES unset  up                    up
GigabitEthernet1/0/23  unassigned      YES unset  up                    up
GigabitEthernet1/0/24  unassigned      YES unset  up                    up
GigabitEthernet1/1/1   unassigned      YES unset  up                    up
GigabitEthernet1/1/2   unassigned      YES unset  up                    up
GigabitEthernet1/1/3   unassigned      YES unset  up                    up
GigabitEthernet1/1/4   unassigned      YES unset  down                  down
Te1/1/1                unassigned      YES unset  down                  down
Te1/1/2                unassigned      YES unset  down                  down
GigabitEthernet2/0/1   unassigned      YES unset  down                  down
GigabitEthernet2/0/2   unassigned      YES unset  down                  down
GigabitEthernet2/0/3   unassigned      YES unset  down                  down
GigabitEthernet2/0/4   unassigned      YES unset  down                  down
GigabitEthernet2/0/5   unassigned      YES unset  down                  down
GigabitEthernet2/0/6   unassigned      YES unset  down                  down
GigabitEthernet2/0/7   unassigned      YES unset  down                  down
GigabitEthernet2/0/8   unassigned      YES unset  down                  down
GigabitEthernet2/0/9   unassigned      YES unset  down                  down
GigabitEthernet2/0/10  unassigned      YES unset  down                  down
GigabitEthernet2/0/11  unassigned      YES unset  down                  down
GigabitEthernet2/0/12  unassigned      YES unset  down                  down
GigabitEthernet2/0/13  unassigned      YES unset  down                  down
GigabitEthernet2/0/14  unassigned      YES unset  down                  down
GigabitEthernet2/0/15  unassigned      YES unset  down                  down
GigabitEthernet2/0/16  unassigned      YES unset  down                  down
GigabitEthernet2/0/17  unassigned      YES unset  down                  down
GigabitEthernet2/0/18  unassigned      YES unset  up                    up
GigabitEthernet2/0/19  unassigned      YES unset  up                    up
GigabitEthernet2/0/20  unassigned      YES unset  up                    up
GigabitEthernet2/0/21  unassigned      YES unset  up                    up
GigabitEthernet2/0/22  unassigned      YES unset  up                    up
GigabitEthernet2/0/23  unassigned      YES unset  up                    up
GigabitEthernet2/0/24  unassigned      YES unset  up                    up
GigabitEthernet2/1/1   unassigned      YES unset  up                    up
GigabitEthernet2/1/2   unassigned      YES unset  up                    up
GigabitEthernet2/1/3   unassigned      YES unset  down                  down
GigabitEthernet2/1/4   unassigned      YES unset  down                  down
Te2/1/1                unassigned      YES unset  down                  down
Te2/1/2                unassigned      YES unset  down                  down
GigabitEthernet3/0/1   unassigned      YES unset  up                    up
GigabitEthernet3/0/2   unassigned      YES unset  up                    up
GigabitEthernet3/0/3   unassigned      YES unset  up                    up
GigabitEthernet3/0/4   unassigned      YES unset  up                    up
GigabitEthernet3/0/5   unassigned      YES unset  up                    up
GigabitEthernet3/0/6   unassigned      YES unset  up                    up
GigabitEthernet3/0/7   unassigned      YES unset  up                    up
GigabitEthernet3/0/8   unassigned      YES unset  down                  down
GigabitEthernet3/0/9   unassigned      YES unset  down                  down
GigabitEthernet3/0/10  unassigned      YES unset  down                  down
GigabitEthernet3/0/11  unassigned      YES unset  down                  down
GigabitEthernet3/0/12  unassigned      YES unset  down                  down
GigabitEthernet3/1/1   unassigned      YES unset  down                  down
GigabitEthernet3/1/2   unassigned      YES unset  down                  down
GigabitEthernet3/1/3   unassigned      YES unset  down                  down
GigabitEthernet3/1/4   unassigned      YES unset  down                  down
Te3/1/1                unassigned      YES unset  down                  down
Te3/1/2                unassigned      YES unset  down                  down
Port-channel1          unassigned      YES unset  up                    up
Port-channel2          unassigned      YES unset  up                    up
Port-channel3          unassigned      YES unset  up                    up
Port-channel4          unassigned      YES unset  up                    up
Port-channel5          unassigned      YES unset  up                    up
Port-channel6          unassigned      YES unset  up                    up
Port-channel7          unassigned      YES unset  up                    up

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